The role of internal reference prices in consumers' willingness to pay judgments: Thaler's Beer Pricing Task revisited.

Alternative reference prices, either displayed in the environment (external) or recalled from memory (internal) are known to influence consumer judgments and decisions. In one line of previous research, internal reference prices have been defined in terms of general price expectations. However, Thaler (Marketing Science 4 (1985) 199; Journal of Behavioral Decision Making 12 (1999) 183) defined them as fair prices expected from specific types of seller. Using a Beer Pricing Task, he found that seller context had a substantial effect on willingness to pay, and concluded that this was due to specific internal reference prices evoked by specific contexts. In a think aloud study using the same task (N = 48), we found only a marginal effect of seller context. In a second study using the Beer Pricing Task and seven analogous ones (N = 144), general internal reference prices were estimated by asking people what they normally paid for various commodities. Both general internal reference prices and seller context influenced willingness to pay, although the effect of the latter was again rather small. We conclude that general internal reference prices have a greater impact in these scenarios than specific ones, because of the lower cognitive load involved in their storage and retrieval.

Extended sensitivity for the calcium selective electrode.

Sensitivity of calcium-selective electrodes heretofore has been limited to calcium concentrations above 10(-8) M in the absence of competing ions. We describe the use of calcium buffers to stabilize the free calcium in the reference electrode. Electrode calibration is linear to 10(-8) M and is curvilinear to 10(-11) M in the presence of 0.1 M ionic strength. Selectivity with respect to competing cations, magnesium, potassium, sodium, and hydrogen is preserved. Electrode response time is less than 2 s for small changes in calcium activity. Response range is linear over 9 log units of calcium activity. Potential-time stability is less than 10 mV/h at saturation currents. Although the silver-silver chloride terminals are photosensitive throughout the visible and near-ultraviolet regions, housing the reference and indifferent in opaque barrels avoids false photovoltaic response.

A combined recycling affinity column-filtration technique.

A new preparative purification technique for biological macromolecules is developed by combining the affinity column chromatography and the membrane filtration technique. A unique feature of the affinity column-filtration apparatus is that the filtrate from the filtration unit is recycled back to the inlet of the affinity column, thus decreasing considerably the total amount of ligands required for the affinity column. A second important feature is that the pump which connects the affinity column and the filtration unit is monitored by an infrared sensor device on the filtration cell; consequently, the flow of the column eluent into the filtration unit is controlled automatically by the solution height in the filtration cell. Highly homogeneous regulatory subunits of type I cAMP-dependent protein kinase from rabbit skeletal muscle are demonstrated to be obtainable by the new purification technique. Thus, this apparatus could have important applications in the purification of a wide range of biological macromolecules. A test for estimating affinity bound proteins is also discussed.

Phosphorylation of the regulatory subunit of type I cyclic AMP-dependent protein kinase by its catalytic subunit.

The regulatory subunit (R) of Type I cAMP-dependent protein kinase from rabbit skeletal muscle can serve as a substrate for its catalytic subunit (C). The degree of phosphorylation depends on both the concentration of C and the the time of incubation. Moreover, the phosphorylation can be totally blocked by protein kinase inhibitors. In contrast, cAMP stimulates the phosphorylation of R using the holoenzyme. The purified holoenzyme isolated from rabbit skeletal muscle can be further fractionated into two fractions on DEAE Sephadex column. The first fraction eluted with low salt (50 mM NaCl) contains a much lower concentration of kinases than the second fraction eluted with high salt (100 mM NaCl), but the low salt kinase can be readily phosphorylated in the presence of MgATP. Our data thus implies that only a small fraction of Type I cAMP-dependent protein kinases in the skeletal muscle is present as the phosphorylatable species.

Chemical cross-linking of cyclic AMP-dependent protein kinase and its dissimilar subunits.

Previous kinetic studies have demonstrated that the activation of cyclic AMP-dependent protein kinase by cyclic AMP involves the formation of a ternary complex of cyclic AMP, the regulatory subunit (R) and the catalytic subunit (C). It is suggested that only this ternary complex breaks down to liberate the enzymically active catalytic subunit. We have performed cross-linking experiments with the holoenzyme and its dissimilar subunits in the presence of MgATP and various concentrations of cyclic AMP. Results from these cross-linking studies indicate that regulatory subunits exist as dimers in the native form. Moreover, dissociation of the holoenzyme or the reconstituted enzyme is promoted by cyclic AMP, and the effect of MgATP is to stabilize the enzyme in the tetrameric form. The success in cross-linking the regulatory and the catalytic subunits of protein kinase with the lysine-specific bifunctional cross-linking reagent dimethyl suberimidate may be attributed to the presence of a large number of lysine residues in the enzyme.

Some effects of cocaine and two cocaine analogs on schedule-controlled behavior of squirrel monkeys.

The behavioral effects of two phenyltropane derivatives of coaine were compared with those of cocaine. Squirrel monkeys responded under multiple fixed-interval, fixed-ratio schedules of either stimulus-shock termination or food presentation or under a fixed-ratio schedule of food presentation. The effects of the three drugs were independent of the type of event that maintained responding. Under the fixed-interval schedules, some doses of each drug increased responding, whereas larger doses generally decreased responding. Maximal increases in responding were similar with each drug. Appropriate doses of each drug increased low response rates, which occurred during the initial segments of the fixed intervals, but had little effect on or decreased higher response rates, which occurred during the later segments of the fixed intervals. Under the fixed-ratio schedules, each drug decreased responding in a dose-related manner. Decreases in fixed-ratio responding resulted both from increased periods of no responding at the beginning of the fixed ratios and from decreased rates of responding once responding began. Each cocaine analog had a slower onset of effect and longer responding began. Each cocaine analog had a slower onset of effect and a longer duration of effect than cocaine. The behavioral effects of the two cocaine analogs were qualitatively similar to those of cocaine, but each was 3 to 10 times more potent than cocaine.